contrast, Kobold B exhibited a thermotolerant community including Sulfobacillus thermosulfidooxidans, Acidithiobacillus caldus, Sulfobacillus sp., Acidithiobacillus sp., Leptospirillum sp., and Leptospirillum ferriphilum. Given its remarkable performance and stability, the Kobold B consortium was deposited at the DSMZ (German Collection of Microorganisms and Cell Cultures) under accession number DSM 35389, and an international PCT patent application was filed (application No. PCT/CL2025/050085). 3.2.Chemical and mineralogical compositions Comprehensive geochemical and mineralogical assessments were performed on the scavenger tailings from the cleaning circuit (CS-CL). These analyses confirmed that cobalt concentrations in direct samples range between 950 and 1100 ppm, consistently exceeding the established success criterion of 80 ppm and affirming the material's potential as a secondary resource for metal recovery. 3.2.1. Elemental analysis and Cobalt concentration Data from two independent sampling campaigns at the San José de Pucobre flotation plant validated the cobalt grades. In the first campaign, 60 kg of homogenized material yielded approximately 1100 ppm of cobalt. The second campaign, involving 150 kg of fresh sample, yielded concentrations between 950 and 1100 ppm, as determined by atomic absorption spectroscopy (AAS). These consistent values substantiate the use of CS-CL tailings as a reliable feedstock for bioleaching operations. 3.2.2. Mineralogical analysis Mineralogical evaluation via TESCAN TIMA and X-ray diffraction (XRD) identified pyrite as the predominant sulfide phase, accounting for approximately 27% (XRD) to 40% (TIMA) of the total mineralogy. Other sulfides were present in trace amounts (<1%). The gangue matrix consists primarily of quartz, followed by chlorite, potassium feldspar, albite, magnetite/hematite, and minor calcite. Other silicates and phosphates were detected at low concentrations, generally below 2%. 3.2.3. Granulometric profile and liberation The granulometric analysis revealed a fine particle size distribution suitable for biooxidation. For the first batch, the median particle size was 28 um and an average of 12 μm within a range of 5 to 241 um. The second batch exhibited a slightly finer profile, with a median close to 27 um whithin a range of 5 to 360 um. Crucially, pyrite demonstrated an exceptional degree of liberation; both batches showed surface liberation exceeding 80% for over 95% of the contained pyrite, a condition that highly favors microbial attachment and oxidative dissolution. 3.3.Biohydrometallurgical performance 3.3.1. Batch Flask Assays
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